Deformation-Resistant Plastic Aerosol Container

ABSTRACT

A plastic aerosol container includes a plastic base portion and a plastic main body portion that is unitary with the plastic base portion and defines a longitudinal axis. The base portion and the main body portion together define an internal space within the container that is pressurized with an aerosol mixture at a pressure that is substantially within a range of about 50 psi to about 300 psi at room temperature. The main body portion has an upper portion that has a first maximum transverse diameter, a lower portion that has a second maximum transverse diameter and an intermediate portion that has a third maximum transverse diameter. The third minimum transverse diameter is less than both the first and second maximum transverse diameters, whereby the main body portion has a narrowed waist portion that provides reinforcement against deformation as a result of pressurization within the internal space of the container. The narrowed waist portion preferably has a substantially constant radius of curvature.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates broadly to the field of containers that are adapted to hold highly pressurized contents, such as aerosol mixtures, and more particularly to a plastic aerosol container having a sidewall construction that is adapted to offer maximum resistance to deformation at high internal pressures.

2. Description of the Related Technology

Aerosol containers have conventionally been fabricated from metal, and are conventionally formed as a cylindrical tube having upper and lower end closures. The bottom end closure is typically shaped as a concave dome, and the upper end closure typically includes a manually actuatable valve for dispensing the pressurized aerosol contents of the container.

Metallic containers have certain inherent disadvantages, such as a tendency to rust over time and to scratch surfaces with which they may come into contact.

Efforts have been made in the past to develop plastic aerosol containers, but have encountered difficulties, mainly relating to controlling the deformation of the plastic material as a result of the significant internal pressurization that is necessary in an aerosol container. Aerosol containers commonly require internal pressures of the magnitude of 50-300 psi, which is significantly greater than pressures that are typically encountered in other packaging applications for which plastic material has been used, such as the packaging of carbonated beverages. Accordingly, design considerations for plastic aerosol containers are quite different than they are for lower pressure packaging applications such as plastic beverage containers.

A plastic aerosol container ideally should be constructed to minimize expansion of the sidewall when it is fully pressurized. If the sidewall is permitted to expand a significant amount, the container is difficult to convey during the manufacturing process, difficult to package in bulk quantities and is space inefficient in a retail facility. If significant deformation occurs in the base portion of the container, it may be unable to effectively support the container on a horizontal surface, both in the retail facility and in the household.

A need therefore exists for an improved plastic aerosol container having a sidewall configuration that is constructed to offer maximum resistance to deformation at high internal pressures.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to provide an improved plastic aerosol container having a sidewall configuration that is constructed to offer maximum resistance to deformation at high internal pressures.

In order to achieve the above and other objects of the invention, a plastic aerosol container that is constructed according to a first aspect of the invention includes a plastic base portion; and a plastic main body portion that is unitary with the plastic base portion and that defines a longitudinal axis. The base portion and the main body portion together define an internal space within the container. The main body portion has an upper portion that has a first maximum transverse diameter, a lower portion that has a second maximum transverse diameter and an intermediate portion that has a third maximum transverse diameter. The third minimum transverse diameter is less than both the first and second maximum transverse diameters, whereby the main body portion has a narrowed waist portion that provides reinforcement against deformation as a result of pressurization within the internal space of the container.

A plastic aerosol container according to a second aspect of the invention includes a plastic base portion and a plastic main body portion that is unitary with the plastic base portion and defines a longitudinal axis. The base portion and the main body portion together define an internal space within the container that is pressurized with an aerosol mixture at a pressure that is substantially within a range of about 50 psi to about 300 psi. The main body portion has an upper portion that has a first maximum transverse diameter, a lower portion that has a second maximum transverse diameter and an intermediate portion that has a third maximum transverse diameter. The third minimum transverse diameter is less than both the first and second maximum transverse diameters, whereby the main body portion has a narrowed waist portion that provides reinforcement against deformation as a result of pressurization within the internal space of the container. The narrowed waist portion preferably has a substantially constant radius of curvature.

These and various other advantages and features of novelty that characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevational view of a plastic aerosol container that is constructed according to a preferred embodiment of the invention;

FIG. 2 is a bottom plan view of the plastic aerosol container that is shown in FIG. 1;

FIG. 3 is a diagrammatical cross-sectional view taken along lines 3-3 in FIG. 2;

FIG. 4 is a cross-sectional view of an aerosol valve assembly for the plastic aerosol container that is depicted in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring now to the drawings, wherein like reference numerals designate corresponding structure throughout the views, and referring in particular to FIG. 1, a plastic aerosol container 10 that is constructed according to a preferred embodiment of the invention is preferably fabricated from a plastic material such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyamide (Nylon), or a blend containing some combination of the same from a plastic preform using a conventional blow molding process such as the reheat stretch blow molding process.

Plastic aerosol container 10 includes a main body portion 12 having a thin oriented sidewall 14, a finish portion 16 that is coupled in a pressure-resistant manner to the aerosol valve assembly 40 that is shown in FIG. 4, and a base portion 18 that is adapted to support the plastic aerosol container 10 on an underlying flat horizontal surface such as a retail shelf or a shelf in a business or household.

The main body portion 12 defines a longitudinal axis 20, and is preferably shaped so that it is substantially symmetrical about the longitudinal axis 20. The main body portion 12, base portion 18 and finish portion 16 together define an internal space 22 for holding a pressurized aerosol mixture 31, preferably at a high pressure that is substantially within a range of about 50 psi to about 300 psi at room temperature, and more preferably substantially within a range of about 100 psi to about 300 psi at room temperature. Room temperature for purposes of this document is defined as a range that is substantially between about 63 degrees F. to about 77 degrees F.

The aerosol mixture 31 preferably includes a propellant, which could be a liquefied gas propellant or a compressed or soluble gas propellant. Liquefied gas propellants that could be used include hydrocarbon propellants such as propane, isobutene, normal butane, isopentane, normal pentane and dimethyl ether, and hydrofluorocarbon propellants such as difluoroethane (HFC-152a) and tetrafluoroethane (HFC-134a). Compressed and soluble gas propellants that could be used include carbon dioxide (C02), nitrous oxide (N20), nitrogen (N2) and compressed air.

The main body portion 12, the finish portion 16 and the base portion 18 are preferably unitary with each other and in the preferred embodiment are fabricated from a high intrinsic viscosity polyethylene terephthalate material, which most preferably has an intrinsic viscosity that is substantially within a range of about 0.80 to about 0.95.

Referring now to FIGS. 1 and 3, it will be seen that the main body portion 12 has an upper portion 28 having a first maximum transverse diameter D₁, a lower portion 30 having a second maximum transverse diameter D₂ and an intermediate portion 32 positioned between the upper and lower portions 28, 30 having a third minimum transverse diameter D₃ that is less than both the first and second maximum transverse diameters D₁, D₂. Accordingly, the intermediate portion 32 defines a narrowed waist portion that provides reinforcement against deformation as a result of the pressurization within the internal space of the plastic aerosol container 10. The narrowed waist portion is preferably shaped so that it is substantially symmetrical about the longitudinal axis 20.

The upper portion 28 and the lower portion 30 are preferably generally cylindrical in shape, having a flat vertically-oriented sidewall portion as viewed in longitudinal cross-section, which facilitates handling at the production and filling facility.

In the preferred embodiment, the upper and lower portions 28, 30 are shaped so that the first and second maximum transverse diameters D₁, D₂ are substantially equal, and together define a maximum transverse diameter D_(MAX) for the entire main body portion 12 and the entire plastic aerosol container 10.

Preferably, a ratio of the third minimum transverse diameter D₃ to the maximum transverse diameter of the container D_(MAX) is substantially within a range of about 0.50 to about 0.95, more preferably substantially within a range of about 0.65 to about 0.95 and most preferably substantially within a range of about 0.80 to about 0.95.

The narrowed waist portion is preferably shaped to have an outer surface that is concavely curved when viewed in a longitudinal cross-section, as is shown in FIG. 3. The concavely curved outer surface of the narrowed waist portion moreover preferably has a substantially constant radius of curvature R_(C). A ratio of the substantially constant radius of curvature R_(C) to the third minimum transverse diameter D₃ is preferably substantially within a range of about 2.0 to about 7.0, more preferably substantially within a range of about 3.0 to about 6.0, and most preferably substantially within a range of about 3.75 to about 5.0.

The aerosol valve assembly 40 is sealed to the finish portion 16 by a crimped flange 54. Aerosol valve assembly 40 includes a dip tube 42 that is positioned within the internal space 22 of the container 10, and a main body portion 44. A valve stem 46 is biased towards a closed position with respect to the main body portion 44 by means of a spring 48. In the closed position, an orifice 50 is sealed by a gasket 52 so that no product from the internal space 22 is expelled under pressure through the internal passage 56 that is defined within the valve stem 46.

An additional conventional dispensing and directing cap may be mounted in the valve stem 46. When the valve stem 46 is depressed, the orifice 50 is opened and product from the internal space 22 is expelled under pressure through the internal passage 56 and through the dispensing and directing cap as an aerosol spray.

It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

1. A plastic aerosol container, comprising: a plastic base portion; and a plastic main body portion that is unitary with the plastic base portion and that defines a longitudinal axis, the base portion and the main body portion together defining an internal space within the container, and wherein the main body portion has an upper portion that has a first maximum transverse diameter, a lower portion that has a second maximum transverse diameter and an intermediate portion that has a third maximum transverse diameter, and wherein the third minimum transverse diameter is less than both the first and second maximum transverse diameters, whereby the main body portion has a narrowed waist portion that provides reinforcement against deformation as a result of pressurization within the internal space of the container.
 2. A plastic aerosol container according to claim 1, wherein the internal space of the container is pressurized with an aerosol mixture to a pressure that is substantially within a range of about 50 psi to about 300 psi.
 3. A plastic aerosol container according to claim 1, wherein the second maximum transverse diameter is substantially the same as the first maximum transverse diameter.
 4. A plastic aerosol container according to claim 1, wherein one of said first and second maximum transverse diameters represents a maximum transverse diameter of the container.
 5. A plastic aerosol container according to claim 4, wherein a ratio of the third minimum transverse diameter to the maximum transverse diameter of the container is substantially within a range of about 0.50 to about 0.95.
 6. A plastic aerosol container according to claim 5, wherein the ratio of the third minimum transverse diameter to the maximum transverse diameter of the container is substantially within a range of about 0.65 to about 0.95.
 7. A plastic aerosol container according to claim 6, wherein the ratio of the third minimum transverse diameter to the maximum transverse diameter of the container is substantially within a range of about 0.80 to about 0.95.
 8. A plastic aerosol container according to claim 1, wherein the narrowed waist portion is substantially symmetrical about the longitudinal axis.
 9. A plastic aerosol container according to claim 1, wherein the narrowed waist portion has an outer surface that is concavely curved when viewed in a longitudinal cross-section.
 10. A plastic aerosol container according to claim 9, wherein said concavely curved outer surface of the narrowed waist portion has a substantially constant radius of curvature.
 11. A plastic aerosol container according to claim 10, wherein a ratio of the substantially constant radius of curvature to the third minimum transverse diameter is substantially within a range of about 2.0 to about 7.0.
 12. A plastic aerosol container according to claim 11, wherein the ratio of the substantially constant radius of curvature to the third minimum transverse diameter is substantially within a range of about 3.0 to about 6.0.
 13. A plastic aerosol container according to claim 12, wherein the ratio of the substantially constant radius of curvature to the third minimum transverse diameter is substantially within a range of about 3.75 to about 5.0.
 14. A plastic aerosol container according to claim 1, wherein said base portion and said main body portion are fabricated from polyethylene terephthalate using a blow molding process.
 15. A plastic aerosol container according to claim 1, wherein said main body portion is substantially symmetrical about the longitudinal axis.
 16. A plastic aerosol container according to claim 1, wherein said base portion and said main body portion are fabricated from a high intrinsic viscosity polyethylene terephthalate material.
 17. A plastic aerosol container according to claim 16, wherein said high intrinsic viscosity polyethylene terephthalate material has an intrinsic viscosity that is substantially within a range of about 0.80 to about 0.95.
 18. A plastic aerosol container, comprising: a plastic base portion; and a plastic main body portion that is unitary with the plastic base portion and that defines a longitudinal axis, the base portion and the main body portion together defining an internal space within the container; and wherein the main body portion has an upper portion that has a first maximum transverse diameter, a lower portion that has a second maximum transverse diameter and an intermediate portion that has a third maximum transverse diameter, and wherein the third minimum transverse diameter is less than both the first and second maximum transverse diameters, whereby the main body portion has a narrowed waist portion that provides reinforcement against deformation as a result of pressurization within the internal space of the container, said narrowed waist portion having a substantially constant radius of curvature; and the internal space of the container is pressurized with an aerosol mixture to a pressure that is substantially within a range of about 50 psi to about 300 psi.
 19. A plastic aerosol container according to claim 18, wherein a ratio of the third minimum transverse diameter to the maximum transverse diameter of the container is substantially within a range of about 0.50 to about 0.95.
 20. A plastic aerosol container according to claim 18, wherein a ratio of the substantially constant radius of curvature to the third minimum transverse diameter is substantially within a range of about 2.0 to about 7.0. 